Southern Company Interconnection Process Dexter Lewis Research Engineer Research and Technology Management Southern Company
Outline • Southern Company • GPC Solar • Interconnection Process – Application requirements – Distribution impact study – Witness Testing
Southern Company
Southern Company • 45,502 MW of generating capacity – 41% natural gas, 37% coal, 16% nuclear, 6% hydro – PV – 60 MW with 115MW in application process – Hydro – 2,785 MW of generating capacity with 16MW of new capacity planned for next 5 years – Biomass – 128 MW – Landfill Gas – 3.2 MW landfill gas generator in Gulf Power Service Territory
Georgia Power Solar • Georgia Public Service Commission adopted a motion that requires Georgia Power Company to bring online 260MW of solar capacity by 2015 and 265MW by 2017 (525MW total). – 100MW of distributed small ‐ scale generation – 425MW of utility ‐ scale solar • Small generators ( � 100�� ) are eligible to sell their electricity under the Renewable & Non ‐ renewable Tariff (RNR ‐ 7) and the Solar Purchase Tariff (SP ‐ 1). Larger customers ( � 80�� ) may sell their electricity as a Qualifying Facility – RNR ‐ 7 – Company will pay avoided cost – SP ‐ 1 – Company will purchase at 17.00 cents/kWh
GPC Number of Interconnection Requests 1 to 65 Inter
GPC kW Installed/Proposed/Anticipated 1 to 5000kW
GPC Average kW per Interconnection 1 to 1000kw/Inter
GPC Interconnection Process 10 Days +10 Days +10 Days GPC Processes & GPC Conducts Customer Submits GPC and Customer Reviews Application Distribution System Application Package Site Visits Package Studies +45 Days +45 Days +5 Days/+90 Days +10 Days/+30 Days Distributed GPC Conducts GPC Offers Customer Customer pays GPC Generation Interconnection Interconnection Interconnection Cost Interconnection Equipment Study Proposal Upfront Agreement Executed +10 Days +3 Days +7 Days GPC Installs GPC GPC Authorizes +Construction GPC Conducts Facility Up to 155 Days + Interconnection Parallel Operation Acceptance Testing Construction Equipment Facility
Customer Submits Application Package • Facility One ‐ Line Electrical Diagram • Facility Relay and Metering One ‐ Line • Proof of site control in the form of a property tax bill, a lease agreement or other legally binding contract • Application for Distributed Interconnection • Required Technical Data
GPC Interconnection Process GPC Processes & GPC Conducts Customer Submits GPC and Customer Reviews Application Distribution System Application Package Site Visits Package Studies Distributed GPC Conducts GPC Offers Customer Customer pays GPC Generation Interconnection Interconnection Interconnection Cost Interconnection Equipment Study Proposal Upfront Agreement Executed GPC Installs GPC GPC Authorizes GPC Conducts Facility Interconnection Parallel Operation Acceptance Testing Equipment Facility
GPC Conducts Distribution Equipment Study • 15 to 30 Business Days for GPC to conduct and complete DSS of Facilities less than or equal to 2MW after Facility is conceptually finalized by both GPC and Customer. • 25 to 45 Business Days for GPC to complete DSS of Facilities 2MW to 10 MW after Facility design is conceptually finalized by both GPC and Customer.
Distribution Study Practices (Inverter Based) • Less than 25kW – Stamp and Go Procedure – Inverter must be UL Standard 1741 • Less than 1MW – Stiffness Factor Procedure – Engineering Guide for Integration of Distributed Storage and Generation EPRI ID: 1024354 – Stiffness Factor = Isc/Idsg
DPV Hosting Capacity Category Criteria Basis Flag Voltage Overvoltage Normal Voltage (ANSI C84.1) ≥ 1.05 Vpu ≥ 3% at primary ≥ 5% at Voltage Maximum difference in node voltage Voltage secondary Deviation from no PV to full PV ≥ ½ band at regulators Phase voltage deviation (ANSI Voltage Unbalance ≥ 3% C84.1) ≥ 100% normal Loading Thermal Element loading rating Total Fault Total fault current contribution at Protection ≥ 10% increase Contribution each sectionalizing device Forward Flow Forward flow fault current Protection Fault contribution at each sectionalizing ≥ 10% increase Contribution device Sympathetic Breaker zero sequence current due to Protection Breaker ≥ 150A an upstream fault Tripping Reduction of Deviation in breaker fault current for Protection ≥ 10% decrease Breaker Reach feeder faults Breaker/Fuse Fault current increase at fuse relative Protection ≥ 100A increase Coordination to breaker current increase Minimum load at each sectionalizing Protection Anti-Islanding ≥ 50% device Power Individual Individual harmonic voltage ≥ 3% Quality Harmonics magnitude Power Total Total harmonic voltage distortion ≥ 5% Quality Harmonics Control Regulator Increased duty > basecase+1 Control Capacitor Increased duty > basecase+1
CYME Analysis (Inverter Based) • Voltage Violations – 97% to 105% ANSI C84.1 Primary – 3% Voltage Imbalance • Overload Conditions • Neutral current – Total current less than 33% of trip setting • Simulations – Summer peak load without DG – Summer peak load with DG – Valley at 10:00AM – 2:00PM without DG – Valley at 10:00AM – 2:00PM with DG – Locked automation setting testing
CYME Analysis Assumptions • Connected Transformer kVA Load Allocation Model – Use historical peak and valley substation loading information – Locked customer loading for customers > 2MVA – 60% constant impedance & 40% constant power loads • Electronically Coupled Generator – Kw, pf, Fault Contribution (140% of nameplate)
GPC Interconnection Process GPC Processes & GPC Conducts Customer Submits GPC and Customer Reviews Application Distribution System Application Package Site Visits Package Studies Distributed GPC Conducts GPC Offers Customer Customer pays GPC Generation Interconnection Interconnection Interconnection Cost Interconnection Equipment Study Proposal Upfront Agreement Executed GPC Installs GPC GPC Authorizes GPC Conducts Facility Interconnection Parallel Operation Acceptance Testing Equipment Facility
Facility Acceptance Testing • Inverters >250kW • Witness Test – GPC Witness Test Personnel • Required to record and witness test – GPC Switching Personnel • Required to operate the disconnecting of the high side fuse or switch – Customer Setting Engineer • Required to make adjustments to interconnection protection equipment – Customer Test Engineer • Required to perform secondary injection testing on interconnection protection equipment – Customer Systems Operator • Required to perform the customer switching of DC and AC systems – Inverter Control Engineer • Required to make adjustments to set points of the inverter if needed – Customer Representative • Required to sign witness test report upon completion
Facility Acceptance Testing • Transient Overvoltage Test • Single Phase Disconnect Test – Shut down timing – 2 sec disconnect, 5 min reconnect • Inverter Control Mode Test – Control power factor to predetermined set point – 30 min
Site Testing Pictures
Normal Peak Voltage = 400 Volt = 1 PU Maximum Peak reached = 702 Volt = 1.76 PU PASS
Maximum Peak reached = 1100 Volt = 2.75 PU FAIL Normal Peak Voltage = 400 Volt = 1 PU
Maximum Peak reached = 1171 Volt = 2.93 PU Normal Peak Voltage FAIL = 400 Volt = 1 PU Transient Over Voltages last 24 ms
By Comparison, look at the same inverter installed at another location Notice the voltage peaks barely goes above 800 Volts or 2 PU PASS
By Comparison, look at the same inverter installed at another location Notice the voltage peaks barely goes above 800 Volts or 2 PU PASS
Single Phase Open Voltage Test Single Single phase phase opened closed here here Approximately 7 seconds of open phase
After settings on the inverter were changed The inverter takes 2 seconds before shutting down.
Next Steps • Interconnection study with multiple connected DG • Winter peak interconnection study? • Need better estimate of time series impact • Need CBA of constant PF inverter control • Need to share learnings from utility experiences • Southern Company needs to develop a DERMS • Develop strategic plans at all business units for the integration of DER
Questions? Dexter Lewis Research Engineer Research and Technology Management Southern Company
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